/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jasper.tagplugins.jstl.core;

import org.apache.jasper.compiler.tagplugin.TagPlugin;
import org.apache.jasper.compiler.tagplugin.TagPluginContext;

public class Catch implements TagPlugin {

	public void doTag(TagPluginContext ctxt) {

		// flag for the existence of the var attribute
		boolean hasVar = ctxt.isAttributeSpecified("var");

		// temp name for exception and caught
		String exceptionName = ctxt.getTemporaryVariableName();
		String caughtName = ctxt.getTemporaryVariableName();

		// main part to generate code
		ctxt.generateJavaSource("boolean " + caughtName + " = false;");
		ctxt.generateJavaSource("try{");
		ctxt.generateBody();
		ctxt.generateJavaSource("}");

		// do catch
		ctxt.generateJavaSource("catch(Throwable " + exceptionName + "){");

		// if the var specified, the exception object should
		// be set to the attribute "var" defines in page scope
		if (hasVar) {
			String strVar = ctxt.getConstantAttribute("var");
			ctxt.generateJavaSource("    pageContext.setAttribute(\"" + strVar
					+ "\", " + exceptionName + ", PageContext.PAGE_SCOPE);");
		}

		// whenever there's exception caught,
		// the flag caught should be set true;
		ctxt.generateJavaSource("    " + caughtName + " = true;");
		ctxt.generateJavaSource("}");

		// do finally
		ctxt.generateJavaSource("finally{");

		// if var specified, the attribute it defines
		// in page scope should be removed
		if (hasVar) {
			String strVar = ctxt.getConstantAttribute("var");
			ctxt.generateJavaSource("    if(!" + caughtName + "){");
			ctxt.generateJavaSource("        pageContext.removeAttribute(\""
					+ strVar + "\", PageContext.PAGE_SCOPE);");
			ctxt.generateJavaSource("    }");
		}

		ctxt.generateJavaSource("}");
	}

}
